Method of breaking up foamed blastfurnace slag and other smelts



Patented Feb. 1, 1949 MEIKHQD OF. BREAKING UP: FOAMED BIJAST-r' FURNACE SLAG AND OTHER. -SMELTS' MarcclGailai l-latehardg Che-am," England N o llrawing. Application June 3-,-1947-, Serial-'No; 752,276. In Great Britain April 189-1946 Section 1; Public Law 690August8 194s This inventionshasfor its" objectto providean improvedzmethod of breaking up foamed blast furnace slag and other smelts into'pieces' of con-- ven'ient sizez-r- The invention is a development arising out of the inventibmcovered'?by"patent application No.. 534,840, filed May, 9, 1944, for Improved method for the production of'porous. slags or other smelts, and which issued as? Patent No.

2,443,103 outrun r: 8%:31948635 According to the Specification of the said patent the foaming.,.of molte'mslag'or other smelts is effected onaporous bed to which water is supplied under control from below by a system of pipes and jets embedded in the porous bed. The product is a carpet of crude foam, which is left on the bed to solidify, to temper to the required hardness and to cool, whereupon it is removed by various means, such as grabs, or skimmers, or even by man-power, to be subsequently crushed and graded by traditional mechanical crushing and screening methods into a light-weight aggregate for use in the production of light weight concrete and for other uses.

For brittle materials such as foamed slag, the method of crushing requires very careful consideration if the production of a great excess of fine grading, i. e. pulverisation, is to be avoided. Apart from these considerations, the major capital outlay for the installation and operation of a traditional foamed slag production plant is absorbed by the crushing and screening devices.

During full-scale foaming tests I have made for the practical application and development of the invention covered by patent application No. 534,840, filed May 9, 1944, I have discovered that, if, after the completion of the foaming and solidification of the foamed carpet, this carpetwhile still in a glowing or ver hot condition-is chilled by water entering from underneath through the identical water jet system as devised for the actual foaming, the water will partly or fully break up the carpet according to the quantity of water applied and its precise mode of application.

In short, and as a result of my discovery, the method and apparatus described and claimed in the specification of patent application No. 534,- 840, filed May 9, 1944, can fulfill three distinct and separate functions, to wit:

(a) Foam the molten slag or smelt and produce a carpet of crude foam;

(b) Allow for undisturbed solidification and hardening of the foamed carpet;

(a) Break up the solidified foamed carpet by 1 Claim. (Cl. 49-77.5-)

sudden chiliing into aggregate of various-gradirigs:

withoutiany other-unechanic'a'l means and thus withoutthezproductionofr that undue quantity of fines which is inherent in all metl'fods of me chanicalcrushing. :1

The-present invention: is l based.- on r the aforea said-discoveryi Briefly statedthe invention: resides in amethod. of. breaking upcfoamedtblast furnace slag and; other .smelts,--which method: comprises subject-- ing. a masseor carpet .of 'thefoamed slag on the like while. it L is. .stilll glowing or sufficiently? hot, to the effect of a chilling medium or of chilling media suchwise as to cause the mass or carpet to contract suddenly and in consequence thereof to break up into pieces of useful sizes.

Stated in another way, the invention provides for the breaking up of the foam, while still glowing or sufficiently hot and thus contracting, by the effect of a chilling medium or of chilling media applied from below or from top or from any other suitable direction, into aggregate of a useful range of gradings.

Water will normally be used for the breaking up process, for the same reason that it will normally be used for the foaming step, it then bein possible to utilise, for carrying out the process of the present invention, the same apparatus as that described and claimed in the specification of patent application No. 534,840, filed May 9, 1944. 'To this end, after water has been supplied to the jets arranged in the foaming bed or beds, in a quantity suificient to effect the foaming step and the mass of foamed slag has solidified, further water is supplied to the jets while the slag is still glowing or sufficiently hot so as suddenly to chill the mass and thereby cause it to break up into pieces. The size of the pieces will depend upon the quantity of water supplied for the purpose in question and as the quantity can be regulated with the apparatus referred to, it will be appreciated that the extent of breakingup, and consequently the size of the resultant pieces, can also be controlled according to requirements.

In place of the water jets, chilling may be effected by the provision of a separate closed pipe system embedded in the foaming bed and which contains a liquid supplied, in controlled quantity, from a refrigerating plant. In this case the broken up product will be dry as compared with the wet product resulting from the application of water as the chilling medium.

There should be an interval of time between the application of water for foaming and the viously involved.

7 ing bed containing water jets. f foam maybe collected in pits or treated in beds up the foam, that is to say, the two steps should when the foam has become sufficiently set but yet remains hot enough for this medium to have the desired effect. V V 7 With the advent of .the present invention, and

the specification of patent application No. 534,840, filed May 9, 1944, this apparatus has the entirely novel attribute in therart of foamingslags and smelts, that it will not only function for complete foaming but will'also replace and considerably improve upon, accelerate and cheapen the function of crushing. In short, it will act as a combined foaming and crushing plant, producing a product in, many ways better and more desirable than that resulting from the use of hitherto known apparatus, at a fraction of the costs pre- The substance of the present invention; name- 1y, to use water, or other chilling media, for the breaking up of crude foam, can be applied to foam produced otherwise than with the aid of a foam- Thus, the crude for the purpose of the invention, after leaving the'particular foaming apparatus employed,so

Q by utilising the foaming apparatus "described in r 'long as it is still in a glowing or sufficiently hot condition for the chillingstep to have the desired effect.

I claim:

Methodof producing blast furnace slag and other smeltsinfoamed and brokenup condition, comprising the steps of pouring the molten smelt into a container having a bottom constructed of porous material, introducing water through the said bottom so as to have the bottom saturated with water prior to the pouring of the molten smelt which on being poured forms an initially foamed carpet or layer on the said bottom, introducing additional water through the porous bottom to complete the foaming of the smelt, ceasing the water supply, leaving the carpet or layer of foamed smelt to solidify and anneal on the REFERENCES CITED file of this patent:

UNITED STATES PATENT Name n, Date Schol Dec. 7, 1915 The following references are of record in the Number 

